From e4eda884db7930cee434828759064b4711604078 Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Mon, 22 May 2017 12:27:07 -0400 Subject: [PATCH] net: Make IP alignment calulations clearer. The assignmnet: ip_align = strict ? 2 : NET_IP_ALIGN; in compare_pkt_ptr_alignment() trips up Coverity because we can only get to this code when strict is true, therefore ip_align will always be 2 regardless of NET_IP_ALIGN's value. So just assign directly to '2' and explain the situation in the comment above. Reported-by: "Gustavo A. R. Silva" Signed-off-by: David S. Miller --- kernel/bpf/verifier.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 1eddb713b815..c72cd41f5b8b 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -808,11 +808,15 @@ static int check_pkt_ptr_alignment(const struct bpf_reg_state *reg, reg_off += reg->aux_off; } - /* skb->data is NET_IP_ALIGN-ed, but for strict alignment checking - * we force this to 2 which is universally what architectures use - * when they don't set CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS. + /* For platforms that do not have a Kconfig enabling + * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS the value of + * NET_IP_ALIGN is universally set to '2'. And on platforms + * that do set CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, we get + * to this code only in strict mode where we want to emulate + * the NET_IP_ALIGN==2 checking. Therefore use an + * unconditional IP align value of '2'. */ - ip_align = strict ? 2 : NET_IP_ALIGN; + ip_align = 2; if ((ip_align + reg_off + off) % size != 0) { verbose("misaligned packet access off %d+%d+%d size %d\n", ip_align, reg_off, off, size); -- 2.39.2